1. Technical Field of the Invention
The present invention relates to novel cosmetic and/or therapeutic compositions for modifying the growth of body hair and/or of head (cranial) hair, comprising at least one lipoxygenase inhibitor and at least one cyclooxygenase inhibitor.
The present invention more especially relates to novel cosmetic and/or therapeutic compositions that either promote the loss of body hair and/or of head hair, or reduce/retard or prevent the growth thereof, which comprise at least one lipoxygenase inhibitor and at least one cyclooxygenase inhibitor.
2. Description of the Prior Art
It is known to this art that certain polyunsaturated fatty acids, in particular those having 20 carbon atoms, such as arachidonic acid, dihomogammalinolenic acid or alternatively eicosapentaenoic acid, can be converted in vivo by the action of certain specific enzymes contained in living cells, in particular epithelial cells, to certain other eicosanoid-type compounds useful to the human body.
Thus, it is known to this art that the enzymes designated cyclooxygenases generate, from the various fatty acids indicated above, prostaglandin-type and thromboxane eicosanoids, and that the enzymes designated lipoxygenases are, for their part, responsible for the formation of leukotriene-type eicosanoids and other hydroxylated acyclic acids containing 20 carbon atoms. The same given polyunsaturated fatty acid (or substrate) will be able to initiate, according to the nature of the enzyme with which it will have first reacted, the formation of several different metabolites, namely, prostaglandins and leukotrienes, for example.
Polyunsaturated fatty acids, especially those which are C.sub.20 (reactive raw materials), which are destined to be metabolized by the specific action of the cyclooxygenase and lipoxygenase enzymes, are generally provided in the body through certain foods, in particular certain natural oils of animal or plant origin. It is thus possible for this supply to be provided either in direct form (such is the case, for example, for arachidonic acid, which is present as such in egg whites), or indirectly in the form of precursor compounds (compounds which are also deemed "essential fatty acids," which are themselves unsaturated fatty acids, generally C.sub.18 -C.sub.22, such as linoleic, .alpha.-linolenic and .gamma.-linolenic acids) which will be converted by means of human metabolism, according to complex mechanisms which will not be repeated in detail herein, to suitable (namely, metabolizable) substrates for cyclooxygenases and lipoxygenases.
It too is known that the enzymatic conversions described above and the different reaction products which result therefrom exert a substantial influence on the mechanisms of body hair and/or cranial hair growth.
In this regard, the assignee hereof has demonstrated that by promoting either of these two enzymatic pathways, cyclooxygenases or lipoxygenases, in the cells of the skin and/or of the scalp, the growth of the body hair and/or of cranial hair could be modified substantially. This is described in EP-94/402055.
Essentially, this patent application describes promoting one of the pathways relative to the other by the administration of a combination of compounds associating an inhibitor of one of the pathways with a stimulator of the other pathway.
WO-94/27563 and WO-94/27586 describe reducing or even inhibiting the growth of body hair or of head hair by the administration of an effective amount either of a lipoxygenase inhibitor or of a cyclooxygenase inhibitor. The amounts of inhibitors which are recommended range from 1% to 30% by weight, or even more. Experience has shown that the desirable effects begin to be measurable from 5% and are only of practical interest at doses greater than 10% or 15%, if not 20%.
Without detracting from the merits of the above findings, it should be stressed that the compounds generally used may have side effects and may sometimes be toxic above certain doses. The consequence of this is that their application is difficult or even impossible, in particular for cosmetic applications.
Thus, need continues to exist for enhancing the efficacy of lipoxygenase and cyclooxygenase inhibitors, in particular to prevent their use at doses which are quite considerably less than the doses at which the undesirable side effects could appear.